1. Field of the Invention
The present invention relates to a semiconductor device manufacturing method.
2. Description of the Related Art
Regarding solid-state image pickup devices as one type of semiconductor device, a solid-state image pickup device including an optical waveguide has recently been proposed to increase a quantity of light incident on a photoelectric conversion portion.
Japanese Patent Laid-Open No. 2010-103458 discloses a solid-state image pickup device including a waveguide that is made up of a clad layer having a low refractive index, and a core layer having a high refractive index and buried in a groove surrounded by the clad layer. As an exemplary method of manufacturing such a solid-state image pickup device, there is disclosed a method of forming the core layer over an entire surface of the clad layer in which an opening is formed corresponding to the photoelectric conversion portion. Examples of materials usable as the core layer include a silicon nitride film (SiN), a silicon oxynitride film (SiON), and silicon carbide film (SiC).
The related-art method of manufacturing the solid-state image pickup device has a difficulty in forming a plug to electrically interconnect electroconductive members, which constitute a wiring, after forming the waveguide. In more detail, when the silicon nitride film (SiN), the silicon oxynitride film (SiON), or the silicon carbide film (SiC) is formed as the core layer of the waveguide, a step of forming a through-hole to provide the plug may become complicated. Thus, it is difficult to form the through-hole with the related art.